/Engine/Source/Runtime/Engine/Classes/Particles/ParticleSystemComponent.h
Set a named random unit vector instance parameter on this ParticleSystemComponent. Updates the parameter if it already exists, or creates a new entry if not.
void SetVectorUnitRandParameter ( [FName](API\Runtime\Core\UObject\FName) ParameterName, const FVector & Param, const FVector & ParamLow )